A surgical instrument of the kind described at the outset is known, for example, from U.S. Pat. No. 6,174,309 B1. This is a scissors-like instrument which unites the functions of scissors and a clamp. In particular, when suitable conductive contacts are provided on at least one clamping member and/or on the severing member, such an instrument can be used for grasping and for severing tissue with simultaneous coagulation of the tissue. It is, therefore, suited, in particular, for performing two steps to be taken during surgery, namely the severing and the coagulating, in a single step, with the tissue to be severed being able to be held with the instrument before, during and after the severing.
A disadvantage of the known instruments is, however, that the severing member may come into contact in an undesirable manner with the clamping member, thereby causing a short circuit, in particular, when both the at least one clamping member and the severing member are connected to a power supply unit, for example, a high-frequency generator, when inserting the severing member into the clamping member opening. Such short circuits are, however, undesired, as they may result in burning of the tissue accompanied by strong carbonization. Also, tissue may thus undesirably adhere or become stuck to the electrically conductive surfaces of the instrument and thereby increase their resistance.
Therefore, it would be desirable to provide an instrument of the kind described at the outset which reliably prevents short circuits between the at least one clamping member and the severing member.